An IC lead pin for PGA is provided by blazing, to be an electric input/output terminal on a back surface of a substrate having a semiconductor element mounted thereon. As the substrate, use has been made of a ceramics material. For the IC lead pin for PGA, mainly use has been made of Kovar (an Fe—Ni—Co alloy) that has a low thermal expansion coefficient equal to that of the ceramics substrate and that is excellent in tensile stress and repeated bending property.
In recent years, there has been a tendency to use a plastic substrate as the above substrate. In the case of such a plastic substrate, there is no need to employ a material with a low thermal expansion coefficient for an IC lead pin for PGA.
On the other hand, in order to improve function of IC, it is desired to ensure speedy transmission in a CPU (central processing unit) and provide a highly dense IC, and a material with high conductivity is required for an IC lead pin for PGA.